Magnesium deficiency in experiemental animals produces an anemia and a shoartened erythrocyte survival. Expriemental animals with severse magnesium deficiency produce erythorocytes with normal magnesium content, enzyme concentrations and structure. However, once this erythrocyte is subjected to an environment deficient in magnesium (plasma) structural and biochemiocal abnormalities occure which lead to the shortened erythrocyte survival.